This invention relates to a Schottky diode and more particularly to a semiconductor device, the substrate of which is formed of gallium arsenide.
The above-mentioned type of diode is widely accepted in the form of an IMPATT diode, mixer diode or varacter diode operated in microwave or milliwave frequencies. The barrier metal used with the prior art Schottky diode is generally formed of a transition metal such as titanium (Ti), molybdenum (Mo), platinum (Pt) or chromium (Cr). The conventional Schottky barrier prepared from any of the above-listed transition metals has the drawbacks that when the Schottky diode has a higher internal temperature than 250.degree. C., then the barrier is reduced in height and the n value of the forward characteristics of the Schottky diode is increased due to said high reduction of the barrier acting as one of the causes, thereby resulting in the deterioration of the property of said diode as a whole. The above mentioned type of Schottky diode has its internal temperature often raised above 250.degree. C. during operation, giving rise to a decline in this property and in its effective life. With the IMPATT diode, for example, the Schottky barrier temperature unavoidably rises to around 250.degree. C. when a high voltage is applied, even under the condition in which a device is provided to decrease heat resistance as much as possible. While the IMPATT diode is used continuously for long hours, the barrier is gradually reduced in height, leading to a decline in the oscillation characteristics of the diode.